Abstract

Abstract The proteins synthesized by arginine-requiring Escherichia coli during growth or arginine starvation were characterized by polyacrylamide gel electrophoresis in sodium dodecyl sulfate to give size distributions. The proteins made during amino acid starvation were smaller than those made by growing cells. This was true for otherwise isogenic rel − (“relaxed”) and rel + (“stringent”) bacteria. Also using electrophoretic profiles, the peptide chain growth rate was estimated by a novel method based on comparison of theoretically predicted and observed kinetics of pulse labeling protein chains of different sizes. During arginine starvation, the rate was 2–5 amino acids/s for both rel − and rel + cells, compared to 20 amino acids/s for growing cells. The results rule out chain growth-rate differences as an aspect of the “relaxed” phenomenon.

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